Search

The last few decades have seen dramatic changes in the hydrography and biogeochemistry of the Mediterranean Sea. The complex bathymetry and highly variable spatial and temporal scales of atmospheric forcing, convective and ventilation processes contribute to generate complex and unsteady circulation patterns and significant variability in biogeochemical systems. Part of the variability of this system can be influenced by anthropogenic contributions. Consequently, it is necessary to document details and to understand trends in place to better relate the observed processes and to possibly predict the consequences of these changes. In this context we report data from an oceanographic cruise in the Mediterranean Sea on the German research vessel Maria S. Merian (MSM72) in March 2018. The main objective of the cruise was to contribute to the understanding of long-term changes and trends in physical and biogeochemical parameters, such as the anthropogenic carbon uptake and to further assess the hydrographical situation after the major climatological shifts in the eastern and western part of the basin, known as the Eastern and Western Mediterranean Transients. During the cruise, multidisciplinary measurements were conducted on a predominantly zonal section throughout the Mediterranean Sea, contributing to the Med-SHIP and GO-SHIP long-term repeat cruise section that is conducted at regular intervals in the Mediterranean Sea to observe changes and impacts on physical and biogeochemical variables. The data can be accessed at https://doi.org/10.1594/PANGAEA.905902 (Hainbucher et al., 2019), https://doi.org/10.1594/PANGAEA.913512 (Hainbucher, 2020a) https://doi.org/10.1594/PANGAEA.913608, (Hainbucher, 2020b) https://doi.org/10.1594/PANGAEA.913505, (Hainbucher, 2020c) https://doi.org/10.1594/PANGAEA.905887 (Tanhua et al., 2019) and https://doi.org/10.25921/z7en-hn85 (Tanhua et al, 2020).

Since the beginning of the Industrial era, oceanic uptake of CO2 has resulted in the acidification of the ocean ; the pH of ocean surface water has decreased by 0.1 and a further decrease of 0.4 units is expected for the end of the century. These changes have effects on the marine biota, especially on calcifying organisms, like planktonic calcifiers, corals, sea urchins, bivalve mollusks, and then have consequences on the entire trophic chain. The negative impact of ocean acidification could be enhanced in some coastal ecosystems, such as the semi – enclosed shallow northern Adriatic, characterized by the presence of numerous riverine inputs and high variability of its biogeochemical properties. It is also an area with marked anthropogenic pressure, being surrounded by highly industrial regions, in which an acidification process of 0.0025 pHT units/year was previously observed.

Carbonate system’s variations have been investigated, from December 2014 to January 2017, along a transect from the Po river delta to Rovinj (Croatia), to identify the influence of riverine inputs and of the other environmental drivers, as temperature, biological processes and the basin-scale circulation, on the physico-chemical and hydrodynamic conditions of the area.

The considerable amount of anthropogenic carbon dioxide absorbed by oceans since the Industrial Revolution, brought to acidification of the sea on a global scale and it represents one of the worst danger of this century for marine ecosystems. The negative impact of this phenomenon could be greater especially in coastal ecosystems, characterized by a higher variability, like the North Adriatic Sea. The main physical and biological factors characterizing temporal and spatial variability of the carbonate system have been studied, on a seasonal scale, focusing on a representative area of the North Adriatic, composed by a transect from Po delta to Istria. Samplings have been performed on a monthly basis in 6 sampling stations arranged along the transect, at 4 depths. Alkalinity, pH and the major physico-chemical descriptors, like salinity, temperature and dissolved oxygen, have been considered. The preliminary data show a strong influence of riverine waters on the majority of the parameters, indeed, smaller variations of temperature, pHT (25°C), total alkalinity (AT), dissolved inorganic carbonate (DIC) and oxygen concentration have been observed in the oriental sector of the basin (oligotrophic) rather than in the occidental sector (mesotrophic). During spring, with the beginning of stratification, superficial waters were characterized by negative values of apparent oxygen utilization (AOU) and by high values of pH in situ ; index of the prevailing of primary production processes. In the months in which a greater contribution of riverine waters have been found, both alkalinity and DIC were increasing in correspondence with higher nutrients concentration (NO3, PO4 e SiO4). Alkalinity showed a significant negative correlation with salinity (p

The Northern Adriatic Sea is the northernmost basin of the Mediterranean Sea and one of its most productive areas, characterized by a shallow depth and by a dominant cyclonic circulation. The oceanographic and meteorological parameters show a marked seasonal and interannual variability. The major forcings of the system are represented by the significant river inputs along the Italian coast, by the Eastern Adriatic Current-EAC, which brings high salinity and oligotrophic waters from the southern basin, and by the notable sea-level range, relatively to the Mediterranean area. The NAS is subject to multiple anthropogenic impacts, e.g.: nutrient inputs, coastal urbanization, fishing activity, tourism, and maritime trade. The basin has undergone marked eutrophication followed by a phase of oligotrophication and then by a recent increase in nutrient concentrations. The NAS has also been subjected to frequent development of mucilage aggregates until the first decade of the 2000s. The LTER-Italy parent site NAS currently includes four research sites: the Gulf of Trieste, the Gulf of Venice, the Po Delta and Romagna Coast, and the Senigallia-Susak Transect. At each site meteo-oceanographic and biological data, mainly on plankton, are gathered both during oceanographic cruises and at fixed point observatories. Each site is supervised by a research institution that also manages the system of fixed sensors, which record data in near real-time

The Northern Adriatic Sea is the northernmost basin of the Mediterranean Sea and one of its most productive areas, characterized by a shallow depth and by a dominant cyclonic circulation. The oceanographic and meteorological parameters show a marked seasonal and interannual variability. The major forcings of the system are represented by the significant river inputs along the Italian coast, by the Eastern Adriatic Current-EAC, which brings high salinity and oligotrophic waters from the southern basin, and by the notable sea-level range, relatively to the Mediterranean area. The NAS is subject to multiple anthropogenic impacts, e.g.: nutrient inputs, coastal urbanization, fishing activity, tourism, and maritime trade. The basin has undergone marked eutrophication followed by a phase of oligotrophication and then by a recent increase in nutrient concentrations. The NAS has also been subjected to frequent development of mucilage aggregates until the first decade of the 2000s. The LTER-Italy parent site NAS currently includes four research sites: the Gulf of Trieste, the Gulf of Venice, the Po Delta and Romagna Coast, and the Senigallia-Susak Transect. At each site meteo-oceanographic and biological data, mainly on plankton, are gathered both during oceanographic cruises and at fixed point observatories. Each site is supervised by a research institution that also manages the system of fixed sensors, which record data in near real-time